Flexible corrugated-metal wall for collapsible and expansible vessels.



W. M. FULTON. FLEXIBLE CORRUGATED METAL WALL FOR GOLLAPSIBLE ANDEXPANSIBLE VESSELS.

APPLICATION FILED JAN. 11, 1910.

Patented Nov. 15, 1910.

I attommm s I Enron.

wESToN 'M. EULToN,

or KNOXVILLE, TENNESSEE, ASsiGNoE To THE FULTON com- IPANY, OFKNOXVILLE, TENNESSEE, A CORPORATION OF MAINE.

FLEXIBLE CORRUGATED-METAL WALL FOR COLLAPSIBLE AND EXPANSIBLE VESSELS. V

Original application filed May 16, 1906, Serial No. 317,157. Divided andthis application file'd Specification of Letters Patent.

Patented Nov. to, role.

January 11,

1910. Serial No. 537,477.

To all whom it may concern:

Be it known that I, WESTON M. FULTON, of Knoxville, Tennessee, haveinvented a new and useful Improvement in Flexible Corrugated-h letalWalls for Collapsible and Expansible Vessels, which invention is fullyset forth in the following specification.

This invention relates to flexible corrugated metal walls forcollapsible and expansible vessels, and more particularly the inventionrelates to making the seams of such vessels wherein non-weldable metals,such as brass or copper, are employed, and has for its object to providecorrugated collapsible and expansible vessels with seams having thecapability of withstanding the repeated strains due to expansion andcontraction, both under changes of temperature and under the action offlexure during the extension and collapsing of the vessel, withoutweakening the seam and causing the same to part and the vessel to leak.

A further object is to enable the walls of such Vessels to be made ofthin metal of nonweldable character and with deep corrugations wherebyvessels of the character referred to may possess great flexibility and.resiliency combined with durability.

In my prior application, Ser. No. 317,157, filed May 16, 1906, I havedescribed and claimed the method of making flexible corrugated Wallsabove referred to, and, therefore, do not claim such method in thisdivisional application thereof.

In collapsible and expansible metal 'vessels which are to be sensitiveto action of slight variations of temperature or pressure, it hasbeen-common to make their walls of thin resilient metal, such as iron orsteel. Such vessels are often required to be subjected to the corrodingaction of gases,-such as air and steam, as when they are in opencommunication with a Steam boiler, under which conditions they soon rustout and leak. Although steel or iron possesses the advantage of greatresiliency and the further advantage of affording a seam that can beformed by processes of welding, yet it is not suitable in situationswhere oxidizing agencies are present even when the metal is protected bynon-oxidizing coatings such as tin, because of the continuous changingameters of tubing, or the wall must be made up of parts cementedtogether by some process other than welding. To secure the necessaryflexibility in the wall whether made of steel, copper or other metal,the walls must be of requisite thinness and the'corrugations deep.

As far as the present inventor is aware,

the walls of collapsible and expansible vessels heretofore made have hadtheir seams formed by welding, or in case of non-weldable metal, by useof some form of brazed butt seam, the faces of the meeting edges eitherbeing perpendicular to the plane of the sheet metal, or inclined theretoto form a bevel. Such seams necessitate the use of comparatively thicksheet brass or copper, and thereby limit the flexibility andsensitiveness of the corrugated collapsible and expansible vessel. Suchseams are also greatly lacking in durability, because they yield tobending strains, come apart, and

cause leakage. The defective character of such seams arises chiefly fromthe fact that the trend of all such seams is across the thickness of themetal, and when the sheet of metal having such a seam is bent, theconvex side of the bend is under tension while the concave side is undercompression. If in this bend occurs the seam as when the seam isperpendicular to the plane of the corrugations, or when the seam is inthe plane of the bend, the cementing material tends to be pulled apartnear one surface and compressed near the other. Repeated bending strainsduring the to and fro movements of the walls of the vessel, especiallywhen heated highly, as by steam, soon granulates the cementing materialand destroys the seam.

Another cause for the unsatisfactory character of flexible corrugatedwalls having brazed seams of the kind above referred to, lies in thefact that the alloy, such as spelter, used; for cementing the abuttingedges, has not the same tensile strength as the metal constituting thewalls of the vessel. The seams are therefore generally weaker than thebody. A further cause re sides in the fact that the coeflicient ofexpansion of such cementing materials as spelter is different from thatof the copper or brass or like alloys used for making the walls of theexpansible and collapsible vessel. There results in the use of a vesselwith such a seam unequal expansion and contraction between the cementingmaterial and the metal of the wall. Strains are set u between the twowhen the vessel is sub ected to wide ranges of temperature, combinedwith those due to the extensive flexure in the corrugations, therebyresulting in the breaking down of the seam. Although this'inequality inexpansion and contraction exists in uncorrugated or straight-walledtubing, it does not result in serious consequences because such tubesare not also subject to repeated bending strains; but such tendenciesbecome an important factor in the construction of flexible, collapsibleand expansible metal vessels. The walls of such Vessels are to beprovided with deep corru-v gations and are made of thin metal to securesensltiveness to changes of temperature and pressure, and are subjectedto forces not to be reckoned with in the case of straight tubing havingcomparatively thick walls.

It is the object of this invention to provide a corru ated collapsibleand expansible vessel, particularly when made of nonweldable metal, witha seam ,wherein the cementing agent holding the surfaces of the sheetmetal along the seam is distributed in a very thin layer or filmparallel to and in the median plane between the convex and concavesurfaces of the bends whereby flexures at such bends are substantiallywithout effect on the cementing material either to put it undertensional or compression strains, thereby increasing the strength of theseam and increasin the life of the flexible walls of the vesse A furtherobject of the invention is to increase the efliciency of such seams byproviding a cementing material which will have a tensile strength andeoeflicient of expansion substantially the same as that of the metalwalls of the vessel. As for example, in the case of a corrugatedcollapsible and expansible vessel made of soft low brass, I have foundthat an alloy consisting of 60 parts of silver, 25 of copper and 15parts of zinc meets these requirements. In using other metals, otheralloys would be used the selection of the alloy being determined by therequirement that the conditions named above be observed. 1

The inventive idea involved is capable of expression in a variety offorms, some of which are hereinafter described for the purpose ofillustration.

Assuming that a flexible corrugated collapsible and expansible vessel isto be made of a no-n-weldable metal such as brass or copper, I form atube of the sheet metal by bending the sheet into tubular form andlapping the opposing edges so as to form a seam'which will lie in aplane parallel with the surface of the metal composing the wall;introducing between the lapped edges a metallic alloy having acoefiicient of expansion and a tensile strength practically the same asthe metal forming the body of the tube; then applying heat to melt thealloy and pressure to compress the same to a thin film between thelapped edges; and a1- lowing the alloy to congeal under pressure; andfinally providing the tube with deep corrugations to render the sameflexible. These corrugations may assume various forms and dlrectionsrelatively to the axis of the vessel, those preferred being asillustrated in Fig. 1. Although I have described forming the tube firstand then corrugating, I may corrugate first and then form into a tubeand make the seam afterward.

It is an important feature of my invention that the thickness of thecementing material between the surfaces of the seam be reduced to theminimum. This is effected by compressing the seam while the cementingmaterial is molten and holding the seam under pressure while cooling.The extent of pressure necessary to secure the desired results may varybetween that which will compress the cementing material to a minimumthickness without alfecting the sheet metal, to that which will reducethe thickness of the seam nearly to the thickness of the adjoining wallof the tube.

Any suitable means forapplying heat to the seam and compressing the samemaybe employed, but I prefer to employ my improved brazing machinedescribed in my application Serial No. 27 3,7 66, filed August 11, 1903,which is capable of applying a yielding pressure during the act ofbrazing and efl'ectingthe heating by passage of a heating currentthrough the seamto be brazed.

The lap seam described above is at r1 'ht angles to the plane of thecorrugations, ut itmay assume other angles thereto, and yet secure theadvantages of having the cementing alloy in the median plane parallel tothe surface of the wall and substantially uninfluenced by bendingstrains. Instead of using a lap seam, the edges of the sheet may meet asina buttseam and a strip of metal placed over the joint and cemented tothe portions of the wall adjoining the butt seam.

I wall lapping,

- expansion and tensile I Heat suificient to melt the alloy, andprescool to the congealing point of the alloy Figure 1 shows inelevation a portion of a for a collapsible and expansible vessel havinga seam made in accordance with my invention. Fig. 2 is a perspectiveView, and Figs. 4 and 6 end views of a blank tube showing the lap scamin course of making. Figs. 3 and 5 illustrate another form of seamembodying the inventive idea, and Fig. 7 shows details.

Referring to Figs. 2, 4 and 6, a brass or copper metal sheet 1, forexample, is bent into the form of a tube with edges 2, 3 overand 7between these overlapping edges is placed a strip 4 of cementing alloy,preferably of slightly less width than the overlapping edges. The natureof this alloy, as stated above, depends onthe nature of the sheet metalwall 1, and in the case of soft low brass, is preferably composed ofsilver, copper and zinc in the proportions substantially as statedabove, having a coeflicient of strength, as of brass.-

sure suflicient to compress the same, are simultaneously applied toreduce the cementing alloy to a thin film. If desired, the pressure maybe sufficient to reduce the thick ness of the seam nearly or quite tothat of the wall of the tube. While the edges are thus held together,the seam is permitted to and will assume the position shown in Fig. 6.The tube is next corrugated.

The advantages of this form of seam in a corru ated vessel will bemanifest from a consideration of Fig. 7, in which is shown an edge viewof the longitudinal seam as would appear in the flat seam of tube 1,Fig. 6, and the same seam when given a series of bends. It is wellunderstood that the material on and near the convex portion of the bendis under tension, whereas on the concave side, the material is underpressure, and in the central layers the material is undersubstantiallyno strain. As this region is occupied by the very thinlayer of cementing material, the latter is in the best position to beeffective in holdin the edges together under the bending baci and forththat takes lace at the bends in the expanding and col-" apsing of thevessel. Furthermore, the cementing material havin been selected toharmonize with the tens' e strength and coeflicient of expansion of thesheet metal composing the wall, tendency to displacement of vthecementing material is furt thereby rendering the seam peculiarlyefi'ecer lessened,

having the wall.

seam is effective, I prefer to construct the a wall in the manner firstdescribed.

What I claim is 1. A flexible corrugated metal wall having a seamtherein which lies in a plane parallel with the surface of the wall andwhich is cemented by a material different from the metal composing theWall.

2. A flexible corrugated metal wall characterized by having a cementedseam lying in a plane parallel to the surface of said wall, thecementing material of said seam substantially the same tensile strengthand coeflicient of expansion as the metal wall.

3. A flexible corrugated metal wall having a lon itudinal seam thereinwhich is cemente by a material whose tensile strength is the same asthat of the metal composing 4. A flexible corrugated metal wall having alongitudinal seam therein which is cemented with material whosecoelicient of expansion is the same as that of the metal! wall.

5. A flexible corrugated metal wall having a longitudinal seam thereinwhich is cemented with a material whose tensile strength and coeflicientof expansion are both the same as that of the metal composing the wall.

6. A flexible corrugated wall of brass, capable of elongation andcompression along the line of one dimension only, having a longitudinalseam therein lying in a plane parallel with the surface of the wall.

7 A flexible corrugated wall of brass having a longitudinal seam thereincemented with a material whose tensile strength and coeflicient ofexpansion are both the same as the brass composing the wall.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

V WESTON M. FULTON.

